Photonic crystal light emitting device

• US 20060151794A1
• Filed: 03/09/2006
• Published: 07/13/2006
• Est. Priority Date: 10/21/2003
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Krames, Michael R., Wierer, Jonathan J. Jr., Sigalas, Mihail M.
• Granted Patent: US 7,294,862 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate

Abstract

A photonic crystal structure is formed in an n-type layer of a III-nitride light emitting device. In some embodiments, the photonic crystal n-type layer is formed on a tunnel junction. The device includes a first layer of first conductivity type, a first layer of second conductivity type, and an active region separating the first layer of first conductivity type from the first layer of second conductivity type. The tunnel junction includes a second layer of first conductivity type and a second layer of second conductivity type and separates the first layer of first conductivity type from a third layer of first conductivity type. A photonic crystal structure is formed in the third layer of first conductivity type.

Claims

1. A light emitting device comprising:

a III-nitride semiconductor structure including an active region disposed between an n-type and a p-type region;

a photonic crystal structure formed in an n-type region; and

a reflector;

wherein the p-type region is substantially planar and the photonic crystal structure does not extend into the p-type region; and

wherein the reflector and the photonic crystal structure are disposed on opposite sides of the active region.

2. The device of claim 1 wherein the photonic crystal structure comprises a periodic variation in a thickness of the n-type region.

3. The device of claim 1 wherein the photonic crystal structure comprises a planar lattice of holes.

4. The device of claim 3 wherein the lattice has a lattice constant a between about 0.1 λ

and about 10 λ

, where λ

is a wavelength of light emitted by the active region.

5. The device of claim 3 wherein the lattice has a lattice constant a and the holes have a diameter between about 0.1a and about 0.5a.

6. The device of claim 3 wherein the holes have a depth between about 0.05 λ

and about 5 λ

, where λ

is a wavelength of light emitted by the active region.

7. The device of claim 3 wherein the lattice is selected from the group consisting of a triangular lattice, a square lattice, a hexagonal lattice, and a honeycomb lattice.

8. The device of claim 3 wherein the lattice includes more than one lattice type.

9. The device of claim 3 wherein a lattice type, lattice constant, hole diameter, and hole depth are selected to create a predetermined radiation pattern.

10. The device of claim 3 wherein a lattice type, lattice constant, hole diameter, and hole depth are selected to create a radiation pattern having a maximum in power emitted in a direction substantially perpendicular to a surface of the semiconductor structure.

11. The device of claim 3 wherein a lattice type, lattice constant, hole diameter, and hole depth are selected to create a radiation pattern having a maximum in power emitted in a direction substantially 30°

from an axis perpendicular to a surface of the semiconductor structure.

12. The device of claim 3 wherein a lattice type, lattice constant, hole diameter, and hole depth are selected such that at least 50% of total power emitted from the device is emitted in a 45°

cone centered about an axis perpendicular to a surface of the device.

13. The device of claim 3 wherein a lattice type, lattice constant, hole diameter, and hole depth are selected such that at least 25% of total power emitted from the device is emitted in a 30°

cone centered about an axis perpendicular to a surface of the device.